Cache management operations can generally be relatively lengthy. This is becoming increasingly true as the size of caches increases. For example, the time required to perform a writeback invalidate operation to a large cache memory (e.g., 4 MB) may be significant and therefore disruptive to other operations of a processor that uses the cache memory. In the case of multiple processing cores that share the cache memory, the disruption may be exacerbated where the multiple processing cores make multiple lengthy cache management operation requests to the cache memory in close temporal proximity.
Additionally, diagnosing failures in modern processors can be very difficult. This is particularly true with respect to diagnosing failures related to cache memories. This is because the caches may store a large amount of data and may be relatively complex, particularly when multiple processing cores share the cache.
Frequently, the primary debug tool available to developers is software simulation of the processor design. In a common scenario, the developer has a software simulation, or simulator, of the design, and the developer provides an initial state of the processor, including the cache, to the simulator. Given the initial processor state, the simulator executes a target program until the bug manifests. The developer is enabled to look back at the execution history by the simulator to determine when the error was made by the design and by what component of the design.